Supporting plates for the membranes of a dialyzer

ABSTRACT

For use in a dialyzer consisting of a stack of alternate pairs of membranes and supporting plates for these, a supporting plate is provided having connector elements for the supply and discharge of blood moulded in one piece therewith, said connector elements being constructed with a weakened hinging line about which the connector element may be folded from a position entirely outside the contour of the plate to a position in which it overlaps and extends beyond an edge of the plate.

United States Patent 1191 Boe et al. 1 Oct. 2, 1973 SUPPORTING PLATES FOR THE [56] References Cited MEMBRANES OF A DIALYZER UNITED STATES PATENTS 1 Inventors: Christian Throkild Farum; 3,612,28l 10/1971 Leonard .7 23/2585 x Steen Gamwell Dawids, Klampenborg both of Denmark Primary Examiner-Frank A. Spear. Jr. [73] Assignee: Aktieselskabet D Danskg Attorney-Watson, Cole. Grindle & Watson Sukkeri'abrikker, Copenhagen, Denmark 1571 ABSTRACT l22l Filed: July 1971 For use in a dialyzer consisting of a stack of alternate 2 APPL 1 1 4 pairs of membranes and supporting plates for these, a supporting plate is provided having connector elements i for the supply and discharge of blood moulded in one l30l Fore'gn Apphcauon Pnomy Data piece therewith, said connector elements being con- July 13, l970 Denmark SH 3642/70 tructed with a weakened hinging line about which the connector element may be folded from a position en- [52] US. Cl. 210/321 tirely outside the contour of the plate to a position in [51] Int. Cl Bold 31/00 which it overlaps and extends beyond an edge of the [58] Field of Search 210/22, 321, SM; 1 t

6 Claims, 5 Drawing Figures Pmminw'z 3.752.555

)K G/G/JQ 1N VENTORS CHRISTIAN T. BOE

STEEN G. DAWIDS ATTORNEY SUPPORTING PLATES FOR THE MEMBRANES OF A DIALYZER BACKGROUND OF THE INVENTION The invention relates to a supporting plate for the membranes of a dialyzer, particularly for hemodialysis, said plate being provided on both sides with projections adapted to support a membrane and in conjunction with such membrane to form flow paths for the dialysis liquid from one end of the sheet to the other, the blood flowing on the opposite side of the membrane, connector elements being provided for clamping between a pair of membranes supported by consecutive supporting plates of a stack of such plates alternating with pairs of membranes, said connector elements having connector passages communicating with inlet and outlet conduits extending transversely of the planes of the supporting plates and membranes.

Dialyzers of this kind usually comprise a plurality of membranes which are arranged in pairs between the said supporting plates so that the blood flows in a relatively thin layer between the two membranes of each pair. The dialysis liquid flows on the opposite side of the membranes in passages formed by the projections which at the same time support the membrane, the latter being slightly deformed between the projections and thereby forming corresponding passages for the flow of blood. The membranes may either be separate sheets or may be formed by a continuous length of suitable semipermeable material folded in zigzag between and around the edges of the supporting plates. The assembly of the stacked membranes and plates may be clamped together by means of bolts placed outside the periphery of the plates and the membranes.

In a known dialyzer of the kind described, the blood is introduced between the membranes throughloose tubular connector elements which are pushed from the exterior in between the membranes of each pair and are sealingly held between opposed ribs uponclamping of the stack.

SUMMARY OF THE INVENTION According to the invention, each of the connector elements is formed in one piece with a supporting plate, being hingedly connected with the main body thereof in such a manner that upon folding of each connector element about the hinge, the opening of its connector passage provides communication to the blood flow passages between the respective pair of membranes.

By this arrangement a simplification of the mounting of the dialyzer is obtained because, unlike what is the case in the known dialyzer mentioned above,there are no loose components to be accurately placed relative to the membranes and the plates. Moreover, sealing problems due to non-uniform properties of materials are avoided because the connector elements are made not only from the same material as the plates but also in the same operation as those, e.g., by injection moulding.

In a preferred embodiment of the invention the connector passage is open towards one of the surfaces of the connector element. Hereby the mould portionused for producing the connector passage may be made in one piece with the mould portion serving as a core to form the through passage in the connector element forming part of the main conduit, whereby a smooth transition can be obtained between the two passages without danger of the formation of moulding fins. This reduces the danger of destruction of the erythrocites, the so-called hemolysis, or of the blood platelets, and also the danger of clotting with precipitation of fibrin. The mould equipment is also simplified because a retractable core for the transverse connector passage is avoided.

For simplification of manufacture and mounting, the connector elements are preferably located at two corners of the plate and are connected with one edge thereof by means of a hinge joint forming an angle of 45 with the edge.

Each connector element may have a portion which upon folding of the element about the hinge joint extends beyond the contour of the plate and is constructed with a through passage communicating with the connector passage, said through passage forming part of an inlet or outlet conduit of the stacked dialyzer.

If the plate has a marginal sealing rib extending along thewhole of the periphery of the plate, a similar sealing rib may advantageously be provided around the through passage of the foldable connector element, the sealing rib of the connector element joining that of the plate in the folded position of the connector element. In this manner a continuous sealing of the membranes is obtained along the whole contour of the layer of blood.

According to a further feature of the invention, the marginal sealing rib of the plate may be split up, at both sides of the portion where the connector element is folded against the edge of the plate, into a plurality of parallel ribs, the connector element being provided on both sides of the connector passage with similar ribs differing from those of the plate in number and spacing. When the difference between the spacing of the ribs is of the same order of size as'the width of the ribs, the said arrangement will ensure that even in the case of small lateral displacements of the two sets of ribs on the main portion of the plate and on the foldable connector element, respectively, there will in practice always be two ribs of the respective sets which are located in continuation of one another, thereby ensuring proper sealing of the layer of blood.

BRIEF DESCRIPTION OF THE DRAWINGS.

FIG. 1 shows a plane view of a supporting plate according to one embodiment of the invention before the plate is stacked in a dialyzer,

FIG. 2 a fraction of one corner of the plate upon folding of a connector element,

FIG. 3 a section along the line III-III of FIG. 1 showing four plates and a continuous membrane sheet folded therebetween, such as these parts will be located in the finished dialyzer, the plates and the membrane sections being, however, drawn apart to improve the illustration,

FIG. 4 a section on a larger scale along the line lV--IV in FIG. 2 showing three successive membrane sections which for clarity are omitted in FIG. 2, and

FIG. 5 a section on a somewhat enlarged scale along the line V-V in FIG. 2.

The figures of the drawings are in part diagrammatical.

DESCRIPTION OF THE PREFERRED EMBODIMENT.

FIG. 1 shows a substantially rectangular supporting plate 1 which is provided on both faces with a multitude of supporting ribs 2 for a semipermeable dialyzer membrane 3, see FIG. 3. At the ends of the supporting area formed by the ribs 2 the plate is constructed at both ends with chambers 4 and 5 serving to distribute the dialysis liquid supplied to the dialyzer, and to collect the individual flows of dialysis liquid to be discharged from the dialyzer, resectively. In both chambers 4 and 5 ribs 6 are provided which are similarly constructed as the ribs 2, but have greater dimensions and a correspondingly greater spacing. To simplify the illustration, only some of the ribs 2 and 6 are shown, but it is to be understood that these cover the whole of the relevant areas of the surface of the plate in the patterns illustrated. At each of the chambers 4 and 5 one side edge of the plate is cranked outwards, and between the edge and the ribs 6 openings 7 and 8 are provided extending through the whole thickness of the plate. When a number of plates are stacked in the finished dialyzer, as diagrammatically illustrated in FIG. 3, with membranes 3 therebetween, and are clamped tightly together, the openings 7 and 8 of the individual plates form vertical passages extending through the whole stack of plates and being connected through openings in bottom and top plates, not shown, to an inlet conduit and an outlet conduit for the dialysis liquid, respectively.

At the edge of the plate 1 remote from the openings 7 and 8 a projecting lug 9 is provided which by means of a hinge joint 10 is connected with a connector element 11 for the supply and discharge of blood, respectively. The hinge joints 10 are formed by a weakened line extending at 45 with the edges of the plate 1, said weakened line having a reduced thickness as compared with the parts 9 and 11. Thereby each connector element 11 may be folded 180 from the position shown in FIG. 1 to the position shown in FIG. 2, where the connector element overlaps the edge of the plate I. In the edge of the plate a recess 12 is provided, the contour of which, as viewed from the exterior of the plate, is apparent from FIG. 4. The connector element 11 has a similarly profiled portion 13 in one surface of which an open passage 14 is formed which extends from the edge of the portion 13 facing inwards in the folded-in position to an opening 15 extending through the whole thickness of the element 11. When the dialyzer has I been assembled as described by stacking of the plates 1 and membranes 3, the openings 15 form continuous transverse passages for the supply and the discharge, respectively, of blood through openings of the top and bottom plates, not shown, corresponding to the openings provided for the dialysis liquid.

In the mounted dialyzer the plates 1 are fixed in relation to each other and to the top and bottom plates by pin and socket means which are shown in FIG. 5. 0n one side of each lug 9 a downwardly extending pin 16 is provided and on the opposite side a socket 17 is provided in which the pin 16 of an adjacent lug 9 fits closely. Corresponding pins and sockets areprovided on two lugs 18 extending from the end edges of each plate I at the two other corners thereof. The folded-in connector elements are mutually fixed in similar manner by means of pins 19 on one side of the elements and sockets 20 on the opposite side.

Sealing along the edges of the pockets 21 and 22 formed between the plates and the membranes for receiving blood and dialysis liquid, respectively, see FIG. 3, is obtained by means of two marginal sealing ribs extending along the whole of the periphery of each plate 1 on one surface thereof. As illustrated in FIG. 5, these ribs may be in the form of projecting ridges of triangular cross section and having relatively sharp edges. In the areas of the edges of the plates where the portion 13 holds the membrane in the recess 12 of the plate and where the ribs 23 must consequently be interrupted, the said ribs are connected via transverse ribs 24 of similar cross section with three sealing ribs 25. On the portion 13 four similar ribs 26 having a smaller spacing are provided. As is apparent from FIG. 2, this arrangement ensures that notwithstanding small variations of the position of the portion 13 relative to the plate 1 there will always be two of the ribs 25 and 26, respectively, which are practically flush with one another.

FIG. 3 illustrates how the dialyzer is assembled from a continuous membrane sheet 3 and a number of plates 1. It is assumed that the lowest section 3a of the membrane sheet in FIG. 3 has beforehand been placed on top of a plate 1, not shown, which by means of the locking pins 16 is fixed relative to the bottom plate of the dialyzer. The edge of the membrane shown at the left in FIG. 3 is thereby held between the recess 12 of the edge of the plate and the portion 13 of the folded-in connector element 11. At the opposite edge of the plate the membrane sheet is now folded back to form the next membrane section 3b whereafter the the first one of the plates 1 shown in FIG. 3 is placed on top of the membrane sheet and is fixed by means of the pins 16. At this stage the connector element 11 is folded out to the position shown in FIG. 1. The membrane is now folded around the left edge of the plate 1, as indicated by the section 3c in FIG. 3, and is pulled towards the right edge of the plate to form the membrane section 3d. Thereafter the two connector elements 11 are folded into the position shown in FIGS. 2 and 4 on top of the membrane section 3d, whereby this section is pressed down in the region of the portion 13 to be held between that portion and the recess 12. When the connector elements 11 have been fixed by means of their pins 19 and the sockets 20 of the connector element next below, the membrane sheet may again be folded at the right edge of the plate 1 to form the return section 3e, whereafter the next plate 1 is placed in position and the building up is continued in the manner described until the desired number of layers has been formed. The dialyzer is thereafter completed by the previously mentioned top plate and the external clamping members, not shown, are mounted.

As will be apparent from the above description and from the drawings, especially FIGS. 3 and 4, the successive sections of the membrane 3a and 3b, 3d and 3e, etc. form individual blood pockets 21 which are closed along their edges, the membrane sections being clamped at the two short end edges of the plates 1 between the upwardly facing sealing ribs 23 of one plate and the smooth bottom face of the other plate. At the edge shown to the right in FIG. 3 each pocket is closed on account of the folding of the membrane sheet and the left edge of the pocket is likewise closed by the clamping between the two plates with exception of the areas of the recesses 12 and the complementary portions 13. In these areas the passages 14 of the portions 13 provide communication between the blood pockets and the through passage for the supply and discharge of blood, respectively, formed by the openings 15.

However, apart from this communication the pocket is also closed in this area, a peripheral sealing rib 27 being provided around the opening 15 and being continued in two ribs 28 along the passage 14 which ribs are again continued in the above mentioned ribs 26 that join the ribs 25 of the plate.

The corresponding pockets 22 for the flow of dialysis liquid between the supply opening 7 and the discharge opening 8 are formed between the plates 1 and the individual sections of the membrane 3 which close the pockets at the left side in FIG. 3, the sealing along the remaining edges being produced by the ribs 23 with or without intervening membrane sections.

In operation of the dialyzer the dialysis liquid is distributed in each pocket 22 from the opening 7 by means of the longitudinal and transverse passages between the ribs 6 to the individual generally longitudinal flow passages defined by the ribs 2 in the main section of the plate 1, whereafter the liquid flows to the opening 8 through the passages, not shown, formed between the ribs 6 in the chamber 5. In the blood pockets 21 similar distribution, principal flow, and collecting passages for the blood are formed by virtue of the engagement of the membrane sections with the ribs 2 and 6, the blood flowing on the opposite side of the membrane sections, whereby the desired diffusion of poisonous matter from the blood to the dialysis liquid takes place in known manner. Details of the construction of the supporting ribs of the plates 1 and the flow paths for the blood and the dialysis liquid thereby formed are apparent from a co-pending application filed simultaneously with the present application.

We claim:

l. A supporting plate for the membranes of a dialyzer, particularly for hemodialysis, said plate being provided on both sides with projections adapted to support a membrane and in conjunction with such membrane to form flow paths for the dialysis liquid from one end of the plate to the other, the blood flowing on the opposite side of the membrane, connector elements being provided for clamping between a pair of membranes supported by consecutive supporting plates of a stack of such plates alternating with pairs of membranes, said connector elements having connector passages communicating with inlet and outlet conduits extending transversely of the planes of the supporting plates and membranes, characterized in that each of the connector elements is formed in one piece with a supporting plate, being hingedly connected with the main body thereof in such a manner that upon folding of each connector element about the hinge, the opening of its connector passage provides communication to the blood flow passages between the respective pairs of membranes.

2. A supporting plate as in claim 1, characterized in that the connector passage is open towards one of the surfaces of the connector element.

3. A supporting plate as in claim 1, characterized in that the connector elements are located at two corners of the plate and are connected with one edge thereof by means of a hinge joint forming an angle of with the edge.

4. A supporting plate as in claim 1, characterized in that each connector element has a portion which upon folding of the element about the hinge joint extends beyond the contour of the plate and is constructed with a through passage communicating with the connector passage, said through passage forming part of an inlet or outlet conduit of the stacked dialyzer.

5. A supporting plate as in claim 4 and of the kind .having a marginal sealing rib extending along the whole element is folded against the edge of the plate, the marv ginal sealing rib of the plate is split up into a plurality of parallel ribs, the connector element being provided I on both sides of the connector passage with similar rib 

1. A supporting plate for the membranes of a dialyzer, particularly for hemodialysis, said plate being provided on both sides with projections adapted to support a membrane and in conjunction with such membrane to form flow paths for the dialysis liquid from one end of the plate to the other, the blood flowing on the opposite side of the membrane, connector elements being provided for clamping between a pair of membranes supported by consecutive supporting plates of a stack of such plates alternating with pairs of membranes, said connector elements having connector passages communicating with inlet and outlet conduits extending transversely of the planes of the supporting plates and membranes, characterized in that each of the connector elements is formed in one piece with a supporting plate, being hingedly connected with the main body thereof in such a manner that upon folding of each connector element about the hinge, the opening of its connector passage provides communication to the blood flow passages between the respective pairs of membranes.
 2. A supporting plate as in claim 1, characterized in that the connector passage is open towards one of the surfaces of the connector element.
 3. A supporting plate as in claim 1, characterized in that the connector elements are located at two corners of the plate and are connected with one edge thereof by means of a hinge joint forming an angle of 45* with the edge.
 4. A supporting plate as in claim 1, characterized in that each connector element has a portion which upon folding of the element about the hinge joint extends beyond the contour of the plate and is constructed with a through passage communicating with the connector passage, said through passage forming part of an inlet or outlet conduit of the stacked dialyzer.
 5. A supporting plate as in claim 4 and of the kind having a marginal sealing rib extending along the whole of the periphery of the plate, characterized in that a similar sealing rib is provided around the through passage of the foldable connector element, the sealing rib of the connector element joining that of the plate in the folded position of the connector element.
 6. A supporting plate as in claim 5, characterized in that at both sides of the position where the connector element is folded against the edge of the plate, the marginal sealing rib of the plate is split up into a plurality of parallel ribs, the connector element being provided on both sides of the connector passage with similar rib differing from those of the plate in number and spacing. 